Average Position:

Average position is usually a term you will see with in Google Analytics or Google Ads.  It refers to the placement your site or ad shows in the list of other sites.  With non-paid search results the average position is associated with a particular search phrase.  The lower the number the better the result.  In November 2019 Google disabled average position in Google Ads and replaced it with Top and Absolute Top Position percentages.  You can read more about it here: https://support.google.com/google-ads/answer/7501826